I find it interesting that even Thomas Donegan, who has been outspoken against collecting elsewhere, seems here to be far less critical (by the way, thanks for your most recent comments, Thomas). He clearly uses museum specimens a great deal in his own taxonomic work, and I hope he has realized the value they have, and that newer specimens have even more than those from a century ago. In the streaming talk he gave that is now available online from Neotropical Bird Club (
http://www.neotropicalbirdclub.org/Video/agm_2016/Talk3 edit Donegan.mp4), it is instructive that one of his comments is that he experienced problems of "small sample sizes." Indeed, small sample sizes pose a problem in much scientific work (as I'm sure you with your science background can attest). If he admits this is a problem with *what we have in museums now* then it's clear that there is need to acquire more samples to be able to have more robust datasets.
Museum collectors are mindful of what they are doing, contrary to what others here may want you to believe, and as I said above, collecting specimens is done only when we feel that we are not going to harm populations.
A delayed response, after some time in Colombia, including birding of a new site during which no specimens were taken... To get decent sample sizes for diagnosability using specimen biometrics, you are looking at needing 15-20 or more specimens of two populations. I think another way of looking at this topic of sample sizes is: should we not focus on studying other characters, such as voice (which unless you want every recording "vouchered") is less intrusive or plumage (which you can get to demonstrating diagnosis with, using a combination of fewer specimens plus photos) or biometrics based on live data (which are not replicable).
The existing museum record, whilst dispersed and therefore costly and time-consuming to study, is often actually not bad. From what I have seen, few collectors active today consider databases of museum specimens as a whole in looking for species/distribution gaps that may warrant filling and then target their collections; many of them just look for gaps in their own museum's collection and are looking at biggering that, or choose a site on such a basis and collect from it everything that they can. Whilst the information from this may have some presently indeterminate benefits in increasing the materials available to non-specified future students, this is much more difficult to justify than specific targeted usage of collection to address particular research questions.
Much of the museum/collecting community (perhaps Dan included) seems to come from a perspective where avian life is of zero value, although species may need protecting. Under such a philosophy it is easy to justify collecting pretty much anything except the last few Great Auks, Guadelupe Caracaras or New Zealand island endemics. I am not sure that all of the rest of the world sees things that way, however, to the extent that blanket collecting or collecting of long series is considered always to be OK. That is part of why the Kingfisher thing irked so many people. (Partly also because of the self-righteous, emotionally-charged press put out by AMNH about the finding of a bird that was actually promptly killed). If scientists are able to link collecting to particular identified research needs, it becomes an easier conversation in terms of justifying it in a world where people still hunt for fun, destroy forests at an alarming rate and eat meat. We can discuss whether scientists should be taking a lead in good behaviour, but you can't stop them given that other far worse things are generally allowed.
Doggedly clinging to an animal life = zero value, specimens are fundamental to all studies /without vouchers there is no science -type doctrine is though inconsistent versus how we approach studies on human variation and DNA, which makes it questionable in mandatory application to all non-human animals.
Dan, yes I have collected stuff too, but this has been done on a "what is the least possible that I could need for this particular study" basis. And sometimes after capturing, releasing and then returning to a site after initial studies with photographs show that more study is warranted.
I would not go as far to say that there are some questions it is impossible to study without specimens, but the cost and practicalities of making multiple live captures of 5 birds at two different localities and bringing them together to compare their plumage real time under anesthesia, or dropping a CT scanner or X-ray machine off a helicopter into jungle means that it is the only practical way of addressing some questions. Subtle aspects of plumage variation can certainly be observed and lead to field identification by seasoned observers once those differences have been spotted, but demonstrating the existence of those differences in the first place is often nigh impossible without a few specimens. I would just argue that taking a life is a most serious thing to do, and becomes more serious with "higher" organisms", and we have to be really careful and considered about the gravity and necessity of doing this, rather than wondering whether or not it might increase our field number or collection size subject only to a limit on causing extinctions. Sadly, virtually no one else I have spoken to in ornithology seems to share the view that taking a life is something of any materiality when compared to the importance of "having a voucher" or "having better collections". Maybe, as per Morgan, I am appealing to emotion and not reason.
